Permanent magnet temperature detection method, device and equipment and permanent magnet traction system

Abstract

The invention discloses a permanent magnet temperature detection method, device and equipment and a permanent magnet traction system, and relates to the technical field of rail transit, and the disclosed permanent magnet temperature detection method comprises the steps: determining the current short-circuit current of a permanent magnet motor; obtaining a preset temperature mapping relationship, wherein the preset temperature mapping represents a corresponding relationship between the short-circuit current and the permanent magnet temperature; and determining a target permanent magnet temperature corresponding to the current short-circuit current according to a preset temperature mapping relation. According to the invention, the temperature of the permanent magnet motor can be measured by detecting the current short-circuit current of the permanent magnet motor and combining the preset temperature mapping relation representing the corresponding relation between the short-circuit current and the temperature of the permanent magnet without observing the change of the flux linkage in operation of the permanent magnet motor, and the accuracy of temperature measurement of the permanent magnet is effectively improved.

Description

Technical Field

[0001] The present application relates to the field of rail transit technology, and in particular to a permanent magnet temperature detection method, device, equipment and a permanent magnet traction system. Background Art

[0002] In rail transit traction systems, permanent magnet traction systems are increasingly used in urban rail traction systems due to their advantages of high efficiency, low energy consumption, and strong power.

[0003] The permanent magnet motor in the permanent magnet traction system is the power source for vehicle traction, and its rotor is excited by permanent magnets. Since the permanent magnet temperature of the permanent magnet motor is usually higher than that of conventional motors when it is working, it is particularly important to accurately detect the permanent magnet temperature.

[0004] At present, the commonly used method is to measure the permanent magnet temperature by observing the changes in magnetic flux during the operation of the permanent magnet motor. However, this method is easily affected by the actual operating conditions of the permanent magnet motor and cannot observe the accurate magnetic flux changes. For example, under low-speed conditions, the magnetic flux changes of the permanent magnet motor are relatively weak, which increases the difficulty of observing the magnetic flux changes, and thus leads to low accuracy of the measured permanent magnet temperature. Summary of the invention

[0005] The main purpose of the present application is to provide a permanent magnet temperature detection method, device, equipment and permanent magnet traction system, aiming to solve the technical problem of low accuracy of permanent magnet temperature measurement in the prior art.

[0006] To achieve the above object, the present application provides a permanent magnet temperature detection method, the method comprising:

[0007] determining the present short-circuit current of the permanent magnet motor;

[0008] Acquire a preset temperature mapping relationship, where the preset temperature mapping represents a corresponding relationship between the short-circuit current and the permanent magnet temperature;

[0009] The target permanent magnet temperature corresponding to the current short-circuit current is determined according to the preset temperature mapping relationship.

[0010] In one embodiment, the step of determining the current short-circuit current of the permanent magnet motor comprises:

[0011] Determine the current operating condition of the permanent magnet motor according to the current vehicle speed range and the current torque;

[0012] The current short-circuit current of the permanent magnet motor is determined according to the current operating condition.

[0013] In one embodiment, the step of determining the current operating condition of the permanent magnet motor according to the current vehicle speed range and the current torque includes:

[0014] When the current vehicle speed reaches a preset vehicle speed and the current torque is lower than the preset torque, determining that the current operating condition is a preset coasting condition;

[0015] The step of determining the current short-circuit current of the permanent magnet motor according to the current operating condition comprises:

[0016] When the current operating condition is the preset coasting condition, controlling the permanent magnet motor to be short-circuited;

[0017] When the permanent magnet motor is short-circuited, the current short-circuit current of the permanent magnet motor is collected.

[0018] In one embodiment, when the current operating condition is the preset coasting condition, the step of controlling the permanent magnet motor to be short-circuited includes:

[0019] When the current operating condition is the preset coasting condition, the input end of the permanent magnet motor is short-circuited by controlling the drive circuit.

[0020] In one embodiment, before the step of obtaining the preset temperature mapping relationship, the method further includes:

[0021] Determining the residual magnetism temperature coefficient corresponding to the permanent magnet motor;

[0022] Determining property parameters of a permanent magnet motor, a permanent magnet reference temperature, and a plurality of preset permanent magnet temperatures;

[0023] Determining a short-circuit current theoretical value at each of the preset permanent magnet temperatures according to the residual magnetization temperature coefficient, the property parameter and the permanent magnet reference temperature;

[0024] A theoretical temperature mapping relationship is established according to each of the preset permanent magnet temperatures and the corresponding short-circuit current theoretical value.

[0025] In one embodiment, the step of determining the short-circuit current theoretical value at each of the preset permanent magnet temperatures according to the residual magnetization temperature coefficient, the property parameter and the permanent magnet reference temperature includes:

[0026] Determine the reference temperature residual magnetism, the corresponding area of ​​the permanent magnet flux linkage, the number of wire turns in the stator winding of the permanent magnet motor, and the motor direct axis inductance, wherein the reference temperature residual magnetism, the corresponding area of ​​the permanent magnet flux linkage, the number of wire turns, and the motor direct axis inductance are all attribute parameters of the permanent magnet motor;

[0027] The short-circuit current theoretical value at each preset permanent magnet temperature is determined according to the residual magnetization temperature coefficient, the permanent magnet reference temperature, the reference temperature residual magnetism, the corresponding area of ​​the permanent magnet flux linkage, the number of wire turns and the motor direct axis inductance.

[0028] In one embodiment, after the step of constructing a theoretical temperature mapping relationship according to each of the preset permanent magnet temperatures and the corresponding short-circuit current theoretical value, the method further includes:

[0029] Determining an actual short-circuit current value of the permanent magnet motor at a preset calibration temperature;

[0030] Determine the target short-circuit current theoretical value corresponding to the preset calibration temperature according to the theoretical temperature mapping relationship;

[0031] Determining a current deviation between the actual short-circuit current value and the target short-circuit current theoretical value;

[0032] The theoretical temperature mapping relationship is corrected according to the current deviation to obtain a preset temperature mapping relationship.

[0033] In addition, to achieve the above-mentioned purpose, the present application also proposes a permanent magnet temperature detection device, the device comprising:

[0034] A current acquisition module, used to determine the current short-circuit current of the permanent magnet motor;

[0035] A mapping relationship module, used to obtain a preset temperature mapping relationship, wherein the preset temperature mapping represents a corresponding relationship between a short-circuit current and a permanent magnet temperature;

[0036] The temperature detection module is used to determine the target permanent magnet temperature corresponding to the current short-circuit current according to the preset temperature mapping relationship.

[0037] In addition, to achieve the above-mentioned purpose, the present application also proposes a permanent magnet temperature detection device, which includes: a memory, a processor, and a permanent magnet temperature detection program stored in the memory and executable on the processor, and the permanent magnet temperature detection program is configured to implement the steps of the permanent magnet temperature detection method as described above.

[0038] In addition, to achieve the above objectives, the present application also proposes a permanent magnet traction system, which includes a permanent magnet motor and a computer program. When the computer program is executed by a processor, the steps of the permanent magnet temperature detection method described above are implemented.

[0039] One or more technical solutions proposed in this application have at least the following technical effects:

[0040] The present application determines the current short-circuit current of the permanent magnet motor; obtains a preset temperature mapping relationship, the preset temperature mapping characterizes the correspondence between the short-circuit current and the permanent magnet temperature; and determines the target permanent magnet temperature corresponding to the current short-circuit current according to the preset temperature mapping relationship. Since the present application does not need to observe the change of magnetic flux during the operation of the permanent magnet motor, but detects the current short-circuit current of the permanent magnet motor, combined with the preset temperature mapping relationship that characterizes the correspondence between the short-circuit current and the permanent magnet temperature, the temperature of the permanent magnet motor can be measured. Therefore, the present application can avoid the measurement process being affected by the actual operating conditions of the permanent magnet motor, and can effectively improve the accuracy of the permanent magnet temperature measurement. At the same time, it will not increase the detection cost and reduce the difficulty of implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0042] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0043] Figure 1 This is a flow chart of the first embodiment of the permanent magnet temperature detection method of the present application;

[0044] Figure 2 This is a flow chart of the second embodiment of the permanent magnet temperature detection method of the present application;

[0045] Figure 3 is a schematic diagram of a permanent magnet motor drive circuit proposed according to the third embodiment of the present application;

[0046] Figure 4 This is a flow chart of a third embodiment of a permanent magnet temperature detection method of the present application;

[0047] Figure 5 This is a schematic diagram of the module structure of the permanent magnet temperature detection device of this application;

[0048] Figure 6 A schematic diagram of the structure of a permanent magnet temperature detection device for implementing an embodiment of the present application.

[0049] The purpose, features and advantages of this application will be further described in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0050] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of the present application and are not used to limit the present application.

[0051] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0052] The main solution of the embodiment of the present application is: the permanent magnet temperature detection device determines the current short-circuit current of the permanent magnet motor; obtains a preset temperature mapping relationship, the preset temperature mapping characterizes the correspondence between the short-circuit current and the permanent magnet temperature; determines the target permanent magnet temperature corresponding to the current short-circuit current according to the preset temperature mapping relationship.

[0053] In this embodiment, for the convenience of description, the following description is made by taking the permanent magnet temperature detection device as the execution subject.

[0054] A permanent magnet motor is a motor that uses permanent magnets to provide a magnetic field. The existing method of measuring permanent magnet temperature is easily affected by the actual operating conditions of the permanent magnet motor and cannot accurately observe the flux change, resulting in low accuracy of the measured permanent magnet temperature.

[0055] The present application provides a solution that does not require observation of changes in magnetic flux during the operation of the permanent magnet motor. Instead, the temperature of the permanent magnet motor can be measured by detecting the current short-circuit current of the permanent magnet motor and combining it with a preset temperature mapping relationship that characterizes the correspondence between the short-circuit current and the permanent magnet temperature. This can avoid the measurement process being affected by the actual operating conditions of the permanent magnet motor, effectively improve the accuracy of the permanent magnet temperature measurement, and at the same time, will not increase the detection cost and reduce the difficulty of implementation.

[0056] It should be noted that the execution subject of the embodiment of the present application can be a computing service device applied to a rail transit traction system, especially a permanent magnet traction system, with permanent magnet temperature detection, network communication and program running functions, such as a tablet computer, a personal computer, a mobile phone, etc., or an electronic device capable of realizing the above functions, a permanent magnet temperature detection device, etc. The following takes a permanent magnet temperature detection device (referred to as the detection device) as an example to illustrate this embodiment and the following embodiments.

[0057] Based on this, the present application embodiment provides a permanent magnet temperature detection method, referring to Figure 1 , Figure 1 This is a flow chart of the first embodiment of the permanent magnet temperature detection method of the present application.

[0058] In this embodiment, the permanent magnet temperature detection method includes steps S10 to S30:

[0059] Step S10, determining the current short-circuit current of the permanent magnet motor.

[0060] It should be noted that the above short-circuit current may be the phase current when the three-phase lead wires of the permanent magnet motor are short-circuited.

[0061] In a specific implementation, a current transformer or a current sensor is connected to the three-phase lead wire of the permanent magnet motor. The detection device can control the three-phase lead wire of the permanent magnet motor to be short-circuited, and then collect the current short-circuit current generated when the three-phase lead wire of the motor is short-circuited through the current transformer or the current sensor.

[0062] Step S20, obtaining a preset temperature mapping relationship, wherein the preset temperature mapping represents a corresponding relationship between the short-circuit current and the permanent magnet temperature.

[0063] It should be noted that the above permanent magnet temperature may be the temperature generated by the permanent magnet material of the permanent magnet motor during operation.

[0064] In a specific implementation, the permanent magnet temperature of the permanent magnet motor can be controlled to be a calibrated value, and then the short-circuit current of the permanent magnet motor is collected through a current transformer or a current sensor at the calibrated value, and the above process is repeated to obtain the corresponding short-circuit current under multiple permanent magnet temperature calibrated values, and then each permanent magnet temperature calibrated value is numerically fitted with the corresponding short-circuit current to obtain a preset temperature mapping relationship that characterizes the corresponding relationship between the short-circuit current and the permanent magnet temperature. The preset temperature mapping relationship can be a curve or table of temperature and current. After obtaining the current short-circuit current, the above detection device can obtain the pre-constructed preset temperature mapping relationship locally.

[0065] Step S30: determining a target permanent magnet temperature corresponding to the current short-circuit current according to the preset temperature mapping relationship.

[0066] In a specific implementation, the detection device may traverse a preset temperature mapping relationship based on the current short-circuit current, and query the target permanent magnet temperature corresponding to the current short-circuit current in the preset temperature mapping relationship, thereby realizing the detection of the permanent magnet temperature.

[0067] This embodiment determines the current short-circuit current of the permanent magnet motor; obtains a preset temperature mapping relationship, the preset temperature mapping characterizes the corresponding relationship between the short-circuit current and the permanent magnet temperature; and determines the target permanent magnet temperature corresponding to the current short-circuit current according to the preset temperature mapping relationship. Since this embodiment does not need to observe the change of magnetic flux during the operation of the permanent magnet motor, but detects the current short-circuit current of the permanent magnet motor, combined with the preset temperature mapping relationship that characterizes the corresponding relationship between the short-circuit current and the permanent magnet temperature, the permanent magnet motor temperature can be measured. Therefore, this embodiment can avoid the measurement process from being affected by the actual operating conditions of the permanent magnet motor, and can effectively improve the accuracy of the permanent magnet temperature measurement. At the same time, it will not increase the detection cost and reduce the difficulty of implementation.

[0068] Based on the first embodiment of the present application, the second embodiment of the present application is proposed. In the second embodiment of the present application, the same or similar contents as those of the first embodiment can be referred to the above introduction, and will not be repeated later. Figure 2 , Figure 2 This is a flow chart of the second embodiment of the permanent magnet temperature detection method of the present application.

[0069] In this embodiment, the step S10 may include steps S101 to S102:

[0070] Step S101, determining the current operating condition of the permanent magnet motor according to the current vehicle speed range and the current torque.

[0071] It should be noted that the above vehicle speed may be the speed generated when the vehicle equipped with a permanent magnet motor is driving.

[0072] It is understandable that the above operating conditions may be the performance and operating conditions of the permanent magnet motor under different working conditions.

[0073] In a specific implementation, the above-mentioned detection device can measure the rotation speed of the wheel by installing a wheel speed sensor on the wheel. The wheel speed sensor is usually an optical or electromagnetic device that can generate a pulse signal every time the wheel rotates one circle. The detection device can calculate the rotation speed of the wheel by calculating the number of pulses per unit time, and then deduce the vehicle speed. The permanent magnet motor has a different speed range under different operating conditions. Based on this, different speed ranges can be associated with corresponding operating conditions in advance. The detection device can use the current speed range to determine the current operating condition corresponding to the permanent magnet motor based on this association.

[0074] It should be understood that the train is used as an example for vehicles equipped with permanent magnet motors. Since the operating conditions of urban rail transit vehicle lines are short station spacing, many train stops, frequent starts and stops, and the average station-to-station running time is 2-10 minutes, the entire working characteristics of the permanent magnet motor, that is, the operating conditions may include: the first operating condition corresponding to constant torque acceleration during starting, the second operating condition corresponding to weak magnetic constant power acceleration after the converter terminal voltage reaches the maximum voltage, the low torque coasting condition after reaching the maximum speed, and the constant torque braking condition before stopping at the station.

[0075] For the first working condition, during the starting phase, the motor needs to accelerate from a stationary state to a certain speed. In this phase, the motor current can be controlled to maintain a constant torque output to achieve smooth acceleration. Usually, when the motor voltage value is less than the limit value, the unit current maximum torque control is adopted.

[0076] For the second working condition, when the terminal voltage of the motor reaches the maximum value, in order to continue to accelerate and increase the speed, the motor enters the weak magnetic control state, at which time the motor torque will gradually decrease, while the motor speed will continue to increase to achieve constant power output. This usually occurs when the motor voltage is greater than the limit value, and constant power weak magnetic control is used.

[0077] For coasting conditions, once the motor reaches the maximum speed, in order to maintain this speed, the motor only needs to provide a small torque to overcome air resistance and track friction. At this stage, the motor works in a state close to no-load, and the energy consumption is low.

[0078] For constant torque braking conditions, when the train is about to arrive at the station, it needs to slow down and eventually stop. At this stage, the motor usually switches to power generation mode, and the braking force generated by the motor helps the train slow down. This braking method is called regenerative braking, which can convert part of the kinetic energy back into electrical energy and improve energy efficiency.

[0079] From the above working conditions, it can be seen that under different operating conditions, the vehicle speed is in different ranges. Based on this, the correlation between different vehicle speed ranges and operating conditions can be constructed.

[0080] In a feasible implementation, step S101 may include step S1011:

[0081] Step S1011, when the current vehicle speed reaches a preset vehicle speed and the current torque is lower than a preset torque, it is determined that the current operating condition is a preset coasting condition.

[0082] It should be noted that the above-mentioned preset coasting condition may be the above-mentioned low-torque coasting condition after reaching the maximum vehicle speed.

[0083] The preset vehicle speed may be a threshold value for determining that the vehicle speed has reached the highest level. The preset torque may be a calibration value for determining that the torque has reached a lower level.

[0084] In a specific implementation, since a large traction force is not required under the preset idling condition, and the speed is balanced, the impact on the system is small. Therefore, the permanent magnet motor can be short-circuited under the preset idling condition to measure a relatively stable short-circuit current. Based on this, the above-mentioned detection equipment can compare the current vehicle speed with the preset vehicle speed, and compare the current torque with the preset torque. When the current vehicle speed reaches the preset vehicle speed and the current torque is lower than the preset torque, it is determined that the current operating condition of the permanent magnet motor is the preset idling condition, and the subsequent operation of controlling the short circuit of the permanent magnet motor can be performed.

[0085] Step S102, determining a current short-circuit current of the permanent magnet motor according to the current operating condition.

[0086] In a specific implementation, the above-mentioned detection device can control the short-circuiting of the three-phase lead wires of the permanent magnet motor when the current operating condition is a preset idling condition, and then collect the current short-circuit current generated when the three-phase lead wires of the motor are short-circuited through a current converter or current sensor.

[0087] Further, step S102 may include steps S1021 to S1022:

[0088] Step S1021, when the current operating condition is the preset coasting condition, controlling the permanent magnet motor to be short-circuited.

[0089] In a specific implementation, the permanent magnet motor can be connected to a drive circuit, which is a circuit that drives the permanent magnet motor to operate, and the drive circuit is connected to the three-phase lead wires of the permanent magnet motor. When the detection device detects that the current pre-operating condition is a preset idling condition, it can control the drive circuit to be short-circuited, thereby short-circuiting the three-phase lead wires of the permanent magnet motor and short-circuiting the permanent magnet motor.

[0090] In a feasible implementation, step S1021 may include step S10211:

[0091] Step S10211, when the current operating condition is the preset coasting condition, the input end of the permanent magnet motor is short-circuited by controlling the drive circuit.

[0092] For ease of understanding, refer to Figure 3 This is for illustration only, but not for limitation. Figure 3 Schematic diagram of a permanent magnet motor driving circuit proposed according to the third embodiment of the present application. Figure 3 In the description, a current sensor is used as a device for collecting short-circuit current. The above-mentioned driving short circuit includes: a first capacitor C, a first switch tube SA1, a second switch tube SB1, a third switch tube SC1, a fourth switch tube SA2, a fifth switch tube SB2 and a sixth switch tube SC2. The first switch tube SA1, the second switch tube SB1, the third switch tube SC1, the fourth switch tube SA2, the fifth switch tube SB2 and the sixth switch tube SC2 can all be insulated gate bipolar transistors. When the current operating condition of the detection device is a preset idling condition, the driving short circuit can be driven, and can be connected to the gate of each switch tube, and can output a corresponding signal to control the conduction state of each switch tube. Figure 3 In the embodiment, a switch K1 is provided between the circuit sensor A and the permanent magnet motor PM. Both ends of the first capacitor C are connected to the power supply VDc.

[0093] In the specific implementation, Figure 3As shown, the detection device can control the gate of each switch tube to output the corresponding signal value, control the first switch tube SA1, the second switch tube SB1 and the third switch tube SC1 to be disconnected, and the fourth switch tube SA2, the fifth switch tube SB2 and the sixth switch tube SC2 to be closed, so that the drive circuit is short-circuited. At this time, the three-phase lead wires ( Figure 3 A, B, and C in the figure are short-circuited to short-circuit the input end of the permanent magnet motor and realize short-circuiting the permanent magnet motor.

[0094] Step S1022, when the permanent magnet motor is short-circuited, collecting the current short-circuit current of the permanent magnet motor.

[0095] In a specific implementation, when the permanent magnet motor is short-circuited, the above-mentioned detection device can collect the steady-state short-circuit waveform when the drive circuit is short-circuited through the current sensor, and the current short-circuit current of the permanent magnet motor can be obtained by calculating the effective value of the steady-state short-circuit waveform.

[0096] This embodiment determines that the current operating condition is a preset coasting condition when the current vehicle speed reaches a preset vehicle speed and the current torque is lower than the preset torque; when the current operating condition is the preset coasting condition, the input end of the permanent magnet motor is short-circuited by controlling the drive circuit; when the permanent magnet motor is short-circuited, the current short-circuit current of the permanent magnet motor is collected. Based on this, the current short-circuit current of the permanent magnet motor can be accurately obtained, thereby improving the accuracy of subsequent permanent magnet temperature detection.

[0097] Based on the first and second embodiments of the present application, the third embodiment of the present application is proposed. In the third embodiment of the present application, the same or similar contents as those of the first and second embodiments can be referred to the above introduction, and will not be repeated later. Figure 4 , Figure 4 This is a flow chart of the third embodiment of the permanent magnet temperature detection method of the present application.

[0098] In this embodiment, before the step of obtaining the preset temperature mapping relationship, steps S01 to S04 may also be included:

[0099] Step S01, determining the residual magnetism temperature coefficient corresponding to the permanent magnet motor.

[0100] It should be noted that the above residual magnetism temperature coefficient can be a physical quantity that characterizes the change of residual magnetism of a permanent magnet motor with temperature. The residual magnetism of a permanent magnet motor can be the magnetization intensity that can be maintained in the original direction of the external magnetic field after the permanent magnet is magnetized to a saturated state and the external magnetic field is removed.

[0101] In a specific implementation, the residual magnetism temperature coefficient corresponding to the permanent magnet motor can be obtained by technicians based on the physical properties of the material and the test results during the manufacturing process when the permanent magnet motor leaves the factory. The user can input the residual magnetism temperature coefficient corresponding to the permanent magnet motor into the detection device, based on which the detection device can read the residual magnetism temperature coefficient corresponding to the permanent magnet motor locally.

[0102] Step S02, determining the property parameters of the permanent magnet motor, the permanent magnet reference temperature and a plurality of preset permanent magnet temperatures;

[0103] It should be noted that the above-mentioned attribute parameters can be parameters that define the basic performance and working characteristics of the permanent magnet motor, such as the direct-axis inductance of the motor. In the permanent magnet motor, the axis of the rotor magnetic pole is called the direct axis. When the direct axis or the axis of the permanent magnet coincides with the axis of the stator, the inductance of the stator is the direct-axis inductance of the motor.

[0104] It is understandable that the permanent magnet reference temperature may be a pre-set standard temperature point, such as 20° C., which helps to ensure the consistency and comparability of the test results.

[0105] It should be noted that the above-mentioned preset permanent magnet temperature may be a pre-calibrated value, or a value that can be measured in real time under specific working conditions.

[0106] In a specific implementation, the property parameters of the permanent magnet motor, the permanent magnet reference temperature and multiple preset permanent magnet temperatures can all be pre-input into the detection device for local storage, and the detection device can read the above parameters locally for subsequent construction of a preset temperature mapping relationship.

[0107] Step S03, determining a short-circuit current theoretical value at each of the preset permanent magnet temperatures according to the residual magnetization temperature coefficient, the property parameter and the permanent magnet reference temperature.

[0108] In a specific implementation, the above detection device can calculate the short-circuit current theoretical value using a first preset current formula at any preset permanent magnet temperature. The first preset current formula is:

[0109] Is=X*(1-α*(t-t0))

[0110] Where Is is the theoretical value of short-circuit current, X is the property parameter, α is the residual magnetism temperature coefficient, t is the preset permanent magnet temperature, and t0 is the permanent magnet reference temperature.

[0111] It should be understood that for each different preset permanent magnet temperature, the corresponding short-circuit current theoretical value can be calculated according to the above-mentioned first preset current formula, so as to obtain the short-circuit current theoretical value at each preset permanent magnet temperature.

[0112] In a feasible implementation, step S03 may include steps S031 to S032:

[0113] Step S031, determining the reference temperature residual magnetism, the corresponding area of ​​the permanent magnet flux linkage, the number of wire turns in the stator winding of the permanent magnet motor, and the motor direct axis inductance, wherein the reference temperature residual magnetism, the corresponding area of ​​the permanent magnet flux linkage, the number of wire turns, and the motor direct axis inductance are all attribute parameters of the permanent magnet motor.

[0114] It should be noted that the above-mentioned reference temperature remanence may be the remanence value of the permanent magnet measured in advance at the reference temperature of the permanent magnet.

[0115] In a specific implementation, the above-mentioned reference temperature remanence, the corresponding area of ​​permanent magnet flux linkage, the number of wire turns in the stator winding of the permanent magnet motor, and the remanence temperature coefficient corresponding to the direct-axis inductance permanent magnet motor can all be obtained by technicians based on the physical properties of the material and the test results during the manufacturing process when the permanent magnet motor leaves the factory. Users can query the above-mentioned attribute parameters and input them into the detection equipment, based on which the detection equipment can read the attribute parameters locally.

[0116] Step S032, determining the short-circuit current theoretical value at each preset permanent magnet temperature according to the residual magnetization temperature coefficient, the permanent magnet reference temperature, the reference temperature residual magnetism, the corresponding area of ​​the permanent magnet flux linkage, the number of wire turns and the motor direct axis inductance.

[0117] In a specific implementation, the above detection device can calculate the short-circuit current theoretical value using a second preset current formula at any preset permanent magnet temperature. The second preset current formula is:

[0118] Is=Br0*(1-α*(t-t0))*S*N / Ld

[0119] Where Is is the theoretical value of short-circuit current, Br0 is the reference temperature remanence, α is the remanence temperature coefficient, t is the preset permanent magnet temperature, t0 is the permanent magnet reference temperature, S is the corresponding area of ​​permanent magnet flux linkage, N is the number of wire turns, and Ld is the direct axis inductance of the motor.

[0120] It should be understood that for each different preset permanent magnet temperature, the corresponding short-circuit current theoretical value can be calculated according to the above second preset current formula, so as to obtain the short-circuit current theoretical value at each preset permanent magnet temperature.

[0121] Step S04: constructing a theoretical temperature mapping relationship according to each of the preset permanent magnet temperatures and the corresponding short-circuit current theoretical value.

[0122] In a specific implementation, the above method can be used to obtain the corresponding short-circuit current theoretical value at each preset permanent magnet temperature, and the above detection device can perform numerical fitting on each preset permanent magnet temperature and the corresponding short-circuit current theoretical value to obtain a theoretical temperature mapping relationship that characterizes the corresponding relationship between the short-circuit current and the permanent magnet temperature. After obtaining the current short-circuit current, the above detection device can determine the corresponding permanent magnet temperature through the pre-constructed theoretical temperature mapping relationship.

[0123] In addition, the above detection device may not use the above theoretical temperature mapping relationship. After obtaining the current short-circuit current, the first preset current formula or the second preset current formula may be used to reversely infer the permanent magnet temperature corresponding to the current short-circuit current.

[0124] In a feasible implementation manner, step S04 may further include steps S041 to S044:

[0125] Step S041, determining the actual short-circuit current value of the permanent magnet motor at a preset calibration temperature.

[0126] It should be noted that the preset calibration temperature may be a pre-selected temperature that can be directly measured. For example, the ambient temperature when the permanent magnet motor is not powered on or running, that is, the cold temperature (such as 20° C.) may be used as the preset calibration temperature. The preset permanent magnet temperatures may include the preset calibration temperature.

[0127] In a specific implementation, the above-mentioned detection device can control the permanent magnet motor to short-circuit through a driving circuit when the permanent magnet motor is at a preset calibration temperature, and obtain the actual value of the short-circuit current of the permanent magnet motor at the preset calibration temperature.

[0128] Step S042, determining a target short-circuit current theoretical value corresponding to the preset calibration temperature according to the theoretical temperature mapping relationship.

[0129] In a specific implementation, the detection device may traverse the theoretical temperature mapping relationship based on the preset calibration temperature, and query the short-circuit current corresponding to the preset calibration temperature in the theoretical temperature mapping relationship as the target short-circuit current theoretical value.

[0130] Step S043, determining a current deviation between the actual short-circuit current value and the target short-circuit current theoretical value.

[0131] In a specific implementation, after obtaining the actual short-circuit current value and the target short-circuit current theoretical value of the permanent magnet motor at a preset calibration temperature, the above-mentioned detection device calculates the difference between the actual short-circuit current value and the target short-circuit current theoretical value, takes the absolute value of the difference, and obtains the current deviation.

[0132] Step S044: correcting the preset temperature mapping relationship according to the current deviation.

[0133] In a specific implementation, after calculating the above-mentioned current deviation, the above-mentioned detection device corrects the theoretical temperature mapping relationship according to the current deviation to obtain the final preset temperature mapping relationship, so as to further improve the detection accuracy of the permanent magnet temperature. If the above-mentioned current deviation is zero or small, such as lower than the set threshold, it is determined that the actual value of the short-circuit current is close to the target short-circuit current theoretical value. At this time, there is no need to correct the theoretical temperature mapping relationship, and the theoretical temperature mapping relationship can be directly used as the final preset temperature mapping relationship.

[0134] This embodiment determines the theoretical value of short-circuit current at each preset permanent magnet temperature by combining the residual magnetism temperature coefficient, the property parameter and the permanent magnet reference temperature, or determines the theoretical value of short-circuit current at each preset permanent magnet temperature by combining the residual magnetism temperature coefficient, the permanent magnet reference temperature, the reference temperature residual magnetism, the corresponding area of ​​the permanent magnet flux linkage, the number of wire turns and the motor direct-axis inductance. Then, a theoretical temperature mapping relationship is constructed according to each preset permanent magnet temperature and the corresponding short-circuit current theoretical value, and the theoretical temperature mapping relationship is corrected to obtain the final preset temperature mapping relationship, thereby improving the construction accuracy of the preset temperature mapping relationship, and indirectly improving the detection accuracy of the permanent magnet temperature.

[0135] It should be noted that the above examples are only used to understand the present application and do not constitute a limitation on the permanent magnet temperature detection method of the present application. More simple transformations based on this technical concept are all within the protection scope of the present application.

[0136] This application also provides a permanent magnet temperature detection device, please refer to Figure 5 , Figure 5 This is a schematic diagram of the module structure of the permanent magnet temperature detection device of this application.

[0137] In this embodiment, the permanent magnet temperature detection device includes:

[0138] The current acquisition module 10 is used to determine the current short-circuit current of the permanent magnet motor.

[0139] The mapping relationship module 20 is used to obtain a preset temperature mapping relationship, where the preset temperature mapping represents the corresponding relationship between the short-circuit current and the permanent magnet temperature.

[0140] The temperature detection module 30 is used to determine the target permanent magnet temperature corresponding to the current short-circuit current according to the preset temperature mapping relationship.

[0141] The permanent magnet temperature detection device provided by the present application adopts the permanent magnet temperature detection method in the above embodiment, which can solve the technical problem of low accuracy of permanent magnet temperature measurement in the prior art. Compared with the prior art, the beneficial effects of the permanent magnet temperature detection device provided by the present application are the same as the beneficial effects of the permanent magnet temperature detection method provided by the above embodiment, and other technical features in the permanent magnet temperature detection device are the same as the features disclosed in the above embodiment method, which will not be repeated here.

[0142] The present application provides a permanent magnet temperature detection device, which includes: at least one processor; and a memory connected to the at least one processor in communication; wherein the memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the permanent magnet temperature detection method in the above-mentioned embodiment one.

[0143] Reference below Figure 6 , Figure 6 The structural diagram of the permanent magnet temperature detection device in the embodiment of the present application is provided. The permanent magnet temperature detection device in the embodiment of the present application may include but is not limited to mobile terminals such as mobile phones, laptop computers, digital broadcast receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Descriptions), PMPs (Portable Media Players), vehicle-mounted terminals (such as vehicle-mounted navigation terminals), etc., and fixed terminals such as digital TVs, desktop computers, etc. Figure 6 The permanent magnet temperature detection device shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0144] like Figure 6As shown, the permanent magnet temperature detection device may include a processing device 1001 (such as a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM: Read Only Memory) 1002 or a program loaded from a storage device 1003 to a random access memory (RAM: Random Access Memory) 1004. In RAM1004, various programs and data required for the operation of the permanent magnet temperature detection device are also stored. The processing device 1001, ROM1002 and RAM1004 are connected to each other via a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Typically, the following systems can be connected to the I / O interface 1006: input devices 1007 including, for example, a touch screen, a touchpad, a keyboard, a mouse, an image sensor, a microphone, an accelerometer, a gyroscope, etc.; output devices 1008 including, for example, a liquid crystal display (LCD), a speaker, a vibrator, etc.; storage devices 1003 including, for example, a magnetic tape, a hard disk, etc.; and communication devices 1009. The communication device 1009 can allow the permanent magnet temperature detection device to communicate with other devices wirelessly or by wire to exchange data. Although the figure shows a permanent magnet temperature detection device with various systems, it should be understood that it is not required to implement or have all the systems shown. More or fewer systems may be implemented or have alternatively.

[0145] In particular, according to the embodiments disclosed in the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, the embodiments disclosed in the present application include a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program includes a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network through a communication device, or installed from a storage device 1003, or installed from a ROM 1002. When the computer program is executed by the processing device 1001, the above-mentioned functions defined in the method of the embodiment disclosed in the present application are executed.

[0146] The permanent magnet temperature detection device provided by the present application adopts the permanent magnet temperature detection method in the above embodiment, which can solve the technical problem of low accuracy of permanent magnet temperature measurement in the prior art. Compared with the prior art, the beneficial effects of the permanent magnet temperature detection device provided by the present application are the same as the beneficial effects of the permanent magnet temperature detection method provided by the above embodiment, and other technical features in the permanent magnet temperature detection device are the same as the features disclosed in the method of the previous embodiment, which will not be repeated here.

[0147] It should be understood that the various parts disclosed in this application can be implemented by hardware, software, firmware or a combination thereof. In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0148] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0149] The present application provides a permanent magnet traction system, which includes a permanent magnet motor and a computer program. The computer program is stored on a computer-readable storage medium, and the computer program is used to execute the permanent magnet temperature detection method in the above embodiment.

[0150] The computer-readable storage medium mentioned above in the present application may be, for example, a USB flash drive, but is not limited to electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, systems or devices, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in combination with an instruction execution system, system or device. The program code contained on the computer-readable storage medium may be transmitted using any appropriate medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination of the above.

[0151] The computer-readable storage medium may be included in the permanent magnet temperature detection device; or may exist independently without being assembled into the permanent magnet temperature detection device.

[0152] Computer program code for performing the operations of the present application may be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0153] The flow chart and block diagram in the accompanying drawings illustrate the possible architecture, function and operation of the system, method and computer program product according to various embodiments of the present application. In this regard, each square box in the flow chart or block diagram can represent a module, a program segment or a part of a code, and the module, the program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the square box can also occur in a sequence different from that marked in the accompanying drawings. For example, two square boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each square box in the block diagram and / or flow chart, and the combination of the square boxes in the block diagram and / or flow chart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0154] The modules involved in the embodiments described in this application may be implemented by software or hardware, wherein the name of the module does not constitute a limitation on the unit itself in some cases.

[0155] The permanent magnet traction system provided by the present application includes a computer program for executing the above-mentioned permanent magnet temperature detection method, which can solve the technical problem of low accuracy of permanent magnet temperature measurement in the prior art. Compared with the prior art, the beneficial effects of the permanent magnet traction system provided by the present application are the same as the beneficial effects of the permanent magnet temperature detection method provided by the above-mentioned embodiment, which will not be described in detail here.

[0156] The above descriptions are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A permanent magnet temperature detection method, characterized in that: The method comprises: determining the present short-circuit current of the permanent magnet motor; Acquire a preset temperature mapping relationship, where the preset temperature mapping represents a corresponding relationship between the short-circuit current and the permanent magnet temperature; The target permanent magnet temperature corresponding to the current short-circuit current is determined according to the preset temperature mapping relationship.

2. The permanent magnet temperature detection method according to claim 1, characterized in that: The step of determining the current short-circuit current of the permanent magnet motor comprises: Determine the current operating condition of the permanent magnet motor according to the current vehicle speed range and the current torque; The current short-circuit current of the permanent magnet motor is determined according to the current operating condition.

3. The permanent magnet temperature detection method according to claim 2, characterized in that: The step of determining the current operating condition of the permanent magnet motor according to the current vehicle speed range and the current torque includes: When the current vehicle speed reaches a preset vehicle speed and the current torque is lower than the preset torque, determining that the current operating condition is a preset coasting condition; The step of determining the current short-circuit current of the permanent magnet motor according to the current operating condition comprises: When the current operating condition is the preset coasting condition, controlling the permanent magnet motor to be short-circuited; When the permanent magnet motor is short-circuited, the current short-circuit current of the permanent magnet motor is collected.

4. The permanent magnet temperature detection method according to claim 3, characterized in that: The step of controlling the permanent magnet motor to be short-circuited when the current operating condition is the preset coasting condition comprises: When the current operating condition is the preset coasting condition, the input end of the permanent magnet motor is short-circuited by controlling the drive circuit.

5. The permanent magnet temperature detection method according to any one of claims 1 to 4, characterized in that: Before the step of obtaining the preset temperature mapping relationship, the method further includes: Determining the residual magnetism temperature coefficient corresponding to the permanent magnet motor; Determining property parameters of a permanent magnet motor, a permanent magnet reference temperature, and a plurality of preset permanent magnet temperatures; Determining a short-circuit current theoretical value at each of the preset permanent magnet temperatures according to the residual magnetization temperature coefficient, the property parameter and the permanent magnet reference temperature; A theoretical temperature mapping relationship is established according to each of the preset permanent magnet temperatures and the corresponding short-circuit current theoretical value.

6. The permanent magnet temperature detection method according to claim 5, characterized in that: The step of determining the short-circuit current theoretical value at each of the preset permanent magnet temperatures according to the residual magnetization temperature coefficient, the property parameter and the permanent magnet reference temperature comprises: Determine the reference temperature residual magnetism, the corresponding area of ​​the permanent magnet flux linkage, the number of wire turns in the stator winding of the permanent magnet motor, and the motor direct axis inductance, wherein the reference temperature residual magnetism, the corresponding area of ​​the permanent magnet flux linkage, the number of wire turns, and the motor direct axis inductance are all attribute parameters of the permanent magnet motor; The short-circuit current theoretical value at each preset permanent magnet temperature is determined according to the residual magnetization temperature coefficient, the permanent magnet reference temperature, the reference temperature residual magnetism, the corresponding area of ​​the permanent magnet flux linkage, the number of wire turns and the motor direct axis inductance.

7. The permanent magnet temperature detection method according to claim 5, characterized in that: After the step of constructing a theoretical temperature mapping relationship according to each of the preset permanent magnet temperatures and the corresponding short-circuit current theoretical value, the method further includes: Determining an actual short-circuit current value of the permanent magnet motor at a preset calibration temperature; Determine the target short-circuit current theoretical value corresponding to the preset calibration temperature according to the theoretical temperature mapping relationship; Determining a current deviation between the actual short-circuit current value and the target short-circuit current theoretical value; The theoretical temperature mapping relationship is corrected according to the current deviation to obtain a preset temperature mapping relationship.

8. A permanent magnet temperature detection device, characterized in that: The device comprises: A current acquisition module, used to determine the current short-circuit current of the permanent magnet motor; A mapping relationship module, used to obtain a preset temperature mapping relationship, wherein the preset temperature mapping represents a corresponding relationship between a short-circuit current and a permanent magnet temperature; The temperature detection module is used to determine the target permanent magnet temperature corresponding to the current short-circuit current according to the preset temperature mapping relationship.

9. A permanent magnet temperature detection device, characterized in that: The device comprises: a memory, a processor, and a permanent magnet temperature detection program stored in the memory and executable on the processor, wherein the permanent magnet temperature detection program is configured to implement the steps of the permanent magnet temperature detection method according to any one of claims 1 to 7.

10. A permanent magnet traction system, characterized in that: The permanent magnet traction system comprises a permanent magnet motor and a computer program, and when the computer program is executed by a processor, the steps of the permanent magnet temperature detection method according to any one of claims 1 to 7 are implemented.

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